E39 Electrical Problems Traced to Trunk Lid Harness Wire Chafing (DIY Diagnostic)

Originally Posted by 540 M-Sport

You may need to speak to a dealer parts tech for help finding a part number

A while back, I called both the San Jose and Fremont BMW dealership parts department and both said they didn't know what the part number was even though it's only one of two choices as shown in theis realoem diagram below.

Assuming the right part number is the one everyone asks for (especially the service department), I asked them how many they sell and both said they never sell either one.

Strange. Something doesn't make sense.

If all these wires are breaking, causing strange electrical issues, then the service department is surely looking for and replacing these looms. I'm sure they're not soldering wires.

But, if they're replacing looms ... how come these two BMW parts departments know nothing about it. Somethings not right with my data ...

I spoke to a BMW tech, and he says he has replaced a few in almost every model BMW, including E39's. He doesn't put much faith in parts counter guys, as they can turn over frequently...

Originally Posted by bluebee

A while back, I called both the San Jose and Fremont BMW dealership parts department and both said they didn't know what the part number was even though it's only one of two choices as shown in theis realoem diagram below.

Assuming the right part number is the one everyone asks for (especially the service department), I asked them how many they sell and both said they never sell either one.

Strange. Something doesn't make sense.

If all these wires are breaking, causing strange electrical issues, then the service department is surely looking for and replacing these looms. I'm sure they're not soldering wires.

But, if they're replacing looms ... how come these two BMW parts departments know nothing about it. Somethings not right with my data ...

Had this same problem with the trunk lid wiring harness. I ordered the $200 part from Circle BMW in NJ, did the whole job myself over the course of 5 hours (crimped with genuine BMW Weather-Pak crimps, then soldered, then genuine BMW shrink tube). Wire colors were easy to match up, brown wires are all grounds, the ground shoe is near the passenger rear door as I recall.

The stealer won't do this job for less that $1500 out here, $300 buys you the harness, crimps, a crimp tool, solder and shrink tube plus a 6 pack of microbrew beer. The job was a bit of a pain because you have to lie down in the trunk and work on the harness. Good thing to consider is that you may want to leave some slack in harness so that it's easier to work on and so the new harness isn't strained after you install it.

1 Year later, no problems. And yes, I blew countless fuses, drained the battery 3 times and finally had an "A-Ha" moment when I touched the loom and once again blew Fuse #10 in my '98 528i. Opened up that loom and every wire except 2 of them was broken or crossed against another. Hope some of you find this helpful, it's a time consuming job but I can think of many better things to spend that $1,500 on for my E39

Originally Posted by adischino

I ordered the $200 part

We can add "Fuse 10" to the gremlins that are related to the trunk loom for the DIY. What does Fuse 10 go to anyway?

Given your data, for the 528i, it's harder than I thought to figure out the part number for the wiring harness as there are lots and lots of #3 options in the real oem diagram

From the 528i diagram below, is the part number 61116907260 "Repair Wiring Set For Trunk Lid"?

Originally Posted by bluebee

We can add "Fuse 10" to the gremlins that are related to the trunk loom for the DIY. What does Fuse 10 go to anyway?

Given your data, for the 528i, it's harder than I thought to figure out the part number for the wiring harness as there are lots and lots of #3 options in the real oem diagram

From the 528i diagram below, is the part number 61116907260 "Repair Wiring Set For Trunk Lid"?

Yup, part #4 in that diagram, it's about $150-$200. Like I said, some patience, solder, crimps, a weather-pak crimper, soldering iron, shrink tube and a long weekend are all you need to remedy this gremlin (boggled me for a month or two). The money you save by doing it yourself vs. the stealership leaves you enough (and then some) for a good 6-pack of microbrew beer to celebrate after you're done.

After pulling fuse 10 on my 528, no problems with drain-down of the battery while I waited to fix it. There are some other items not on the loom that are on this circuit that won't work while this fuse is pulled, but nothing vital as I remember.

Originally Posted by adischino

There are some other items not on the loom that are on this circuit that won't work while this fuse is pulled, but nothing vital as I remember.

Nothing vital, I agree. I've been driving for months with my trunk loom a shambles (fixing my life first, but that's another story altogether).

For the record, this thread showed the following symptom & cause:

Symptom:
- Trunk would not open from any button on the key fob

Solution:
- Fixed one broken brown wire (ground) and the gray/green wire (zv drive rear lid, positive)

Note that thread suggests a prophylactic treatment of lubing the wires with high-dielectric grease (e.g. silicone lubricant). Anyone know what that is and where to get it?

This is an amazing thread on the electrical issues within the trunk. I parked my 2000 328ci (e46) for about a week and a half in cold, snowy northeastern weather. When I first drove the car, both license plate lights were out and the warning showed on my instrument cluster. I replaced the lights with new 12v 5A bulbs and they did not come on. I tried a second set of 13.5V 5A bulbs and they still did not come on. The error still showed on my cluster. I scrubbed the terminals with steel wool. Still would not come on. I tested the wire harness by shaking it and bending it to see if I could make the lights flicker but nothing happened. I pulled the top part of the "snorkel" back and inspected the wire harness that enters the trunk. The wires looked fresh and supple. I also checked all the 10A fuses as well as #32 and #9 which seems to be the Light Control Module. I have searched online for other possible causes but I have not had any luck.

Does anyone out there have any additional suggestions as to what this problem could be? I would hate to have to take the car to a service station for such a seemingly simple problem.

Thanks!!

To keep pertinent information in one thread, in this post, it is suggested to spray the inside of the trunk loom with Liquid Wrench brand Silicone Spray Lubricant (Home Depot), which is labeled as "high-dielectric".

Also in that thread, it is stated the trunk loom wires are 18 gauge.

What was reported effective, instead of solder, was using 18-22 AWG bullet splices (Radio Shack or Home Depot) and crimped the connections and wrapped them in electrical tape.

Nicely relevant wiring diagram from this thread ...

Another symptom which points to frayed trunk wires is in this old thread.

The guy's key was the only thing that unlocked the trunk.

The button inside the car, the handle on the trunk, and the key fob did NOT unlock the trunk.

I have the SAME problem (among other things) due to the frayed wires (that I haven't figured out how to repair yet).

It sure would be nice to see pictures of other peoples' repaired trunk loom!

trunk button on deck stopped working after having car repaired from a rear-ender. My inde and I thought maybe the button or the fuse or relay or central lock button might be the culprit. Nope, it was the damn wire loom spliced again.

In the summer of 2009, I repaired the loom and added additional wiring length to repair damaged wires. Now i observe that the exact wires I lengthened are getting cut again. (black stuff on wires is electrical glue)


So this leads me to believe the problem is with the rubber boot being too short, not the loom itself. When I pop the rubber boot cover loose from the deck lid, the loom has ample length to not get caught on the deck. However when the rubber boot is attached, it puts pressure on the loom inside and ends up splicing the wires on the deck lid opening.


For now, I repaired the trunk release wire with e-tape and have left the rubber boot unattached to the deck lid. I will next figure out a way to lengthen the rubber boot by cutting it in the middle and inserting a spring or similar around the exposed loom section, then wrap with shrink wrap tape or similar.

Looks like some engineer at BMW missed the measurement on this item

Originally Posted by aliaw528

I will next figure out a way to lengthen the rubber boot by cutting it in the middle and inserting a spring or similar around the exposed loom section, then wrap with shrink wrap tape or similar.

Thanks for showing the only pics I have ever seen of a REPAIRED trunk loom wiring harness! Nobody seems to want to show off their handiwork!

Also, thanks for coming up with a suggestion as to what the problem is. I too have sliced my trunk loom down the center (although for a different reason ... I needed to access the broken wires which had turtled into the loom).

Here's a pic of my harness, still unrepaired. Whatever idea you come up with for lengthening the rubber snorkel will be of use to me too so keep us informed.

PS: Notice this mostly happens on "blue" BMWs!

I have a 97 528i COLOR WHITE and have experienced the same problem with trunk wires. SO it is not only the BLUE ones.

Originally Posted by Stuart 214

have experienced the same problem with trunk wires

It would be great to see a picture of how you repaired your wires!

to extend the rubber boot for the trunk loom. I re-soldered my broken connection and put shrink wrap on the fixed connection. (make sure you slip the shrink wrap on the wires before you solder them together). Then Home Depot had the flex conduit that is already split down the middle so I used a piece to lengthen the boot. When I repaired the cut wires last year, I used additional wire to lengthen and make the repair a little easier.






Be aware, when you lengthen the boot, it will then want to lie down under the trunk hinge when the trunk closes, getting pinched by the trunk hinge. I had to keep pulling the lower rubber boot higher on the flex conduit to get it so it wouldn't lie directly under the hinge when closing the trunk all the way.

Thank you for the excellent pictures and the idea for extending the trunk loom length!

This is perfect information for others (like me) who still haven't figured out how they'll do the job!

used above as well if you want to repair the wires in the loom properly. But as he stated, that is at least a weekend's worth of work and beer.

Well I finally got tired of the trunk not opening from the key remote or by hand (it would only open with the key itself); and I gathered enuf' courage to tackle the wiring job myself.

The results are decidedly NOT PRETTY. Get ready to close your eyes and tuck the young children under your arms if you dare to read on any further. I'm sure this is a pretty good lesson in what not to do, but, alas, it's done, and it's working.

First thing was I bought a few packs of rather expensive (for what it is) heat shrink tubing. Turns out all that variety was a waste. The only size I used was 3/32" (but nobody told me that ahead of time so I'm telling it to you now).


The next thing I bought was flux and solder and I used a block of wood the floor guys left after fixing my bamboo floors (long story) as a table underneath the wiring loom. I gathered up some spare wire, but it turned out to be huge in diameter compared to the original wire; but I went with it anyway (figuring bigger is better). Dunno if that was a mistake or not.


I'm not the best at soldering but I bought a soldering iron and the guy who sold it to me at Fryes (which is an amazing place ... it's a supermarket for electronic stuff) told me to heat the metal, not the solder. Yeah, fat chance. Anyway, here's me attempting to heat the metal so that the solder would flow on the wires. In the end, I would mostly heat the solder so that the solder would flow on the wires. (I did say this isn't the best example didn't I?)


For each of the many broken wires, I added about six inches of wire, which was probably about four or five inches too much. Again, I didn't say follow me; I'm just telling you what I did. Notice I had to break a couple of wires because (duh) I didn't think about putting the heat-shrink tubing on FIRST before making the final connection. Also notice I didn't follow any color-coding scheme whatsoever. I just connected like colors, hoping that all the browns truly were ground as I couldn't tell them apart.



At this point, I had the bright idea of trying out that liquid electrical tape stuff. So I splashed that stuff on everywhere, especially in the many spots where the insulation was just cracked but the wire hadn't separated yet. This wiring job was getting uglier and uglier by the moment.



Because it was so goopy, I let the brush-on electrical tape dry overnight.

In the morning, when all the goop stopped dripping, I lit up my lousy Bernz-o-matic portable flame thingey, which kept going out, and which was really hard to use. I slid all the 3/32" heat shrink tubes into place, two for each wire, and basically melted those things onto the wires. Dunno if this is going to make a difference or not; but as I said, it's what I did.


There was still that nagging problem of the three or four cracked insulation wires, which, by this time, I had no stomach to cut and solder in an additional length of wire. So, what I resorted to was the unique idea of slicing a 3/32" heat-shrink tube down the middle, placing it over the wire, and heat shrinking it in place.


What happened though was the sliced heat-shrink tubing merely folded outward as it was heated (like a hotdog sliced down the middle) until I hit upon the bright idea of taping the ends closed with electrical tape, which I subsequently burned off as it melted anyway. (I did say this was ugly.)


At this point, I was done with the soldering of the wires and it was now time to tape up the scuba hose itself. Remember, I had to slice this hose down the middle to access broken ends of wires. Also, I added about five inches (which was about four inches too much) of wire, so now the scuba hose was too short to go back to the trunk lid itself. I taped it up anyway.


The penultimate step was to stuff all the loose extra-length wires up into the trunk lid itself, since they were hanging out all over anyway. At this point, I realized adding way too many inches wasn't actually a smart thing; but I was darned if I was going to cut it all apart and start all over. I just don't have the patience for that.


Lastly, I taped up all the wires, and the scuba hose, so that the loom was protected from the chafing at the edge of the trunk lid. I don't actually think this is a good job, so, this example should teach you more what NOT to do than what to do. But, it is what it is.


The good news is that the trunk again opens from the remote button on the key fob; and if the doors are unlocked, I can again open the trunk from outside with my hands. And the lights work again in the trunk!

Nice job, BB! Bottom line, it works. And that's the important thing.

Just a couple of suggestions for those that plan to do a similar job. For the conductor extensions, use a braided wire rather than a solid conductor (that's what the picture looks like). Braided wire is more flexible, allows you to twist wiring together and holds a solder weld better. In lieu of a torch, use a heat gun to shrink the shrink tubing. The heat is less likely to cause a fire or burn paint. Harbor Freight has cheap ones.

Now I gotta run and check my wiring loom!!!

Bluebee, is there not a replacement harness that can be purchased to replace this? Not to question all your hard work, but I would be very suspect of the rest of harness, no telling what the insulation is hiding in damage to the stranded wire underneath from all the flexing it has done over the years.

Originally Posted by bluebee

In looking for the definitive DIY that pulls the harness out for repair or replacement (which I did not find) I did find this E36 DIY ... again with the same problem as we have on the E39 - and again - a BLUE BMW.

Why are only the blue-b's affected! I'm starting to feel a little superstitious ... only Blue B's have posted pictures on the Internet of the busted
trunk wires!

LOL..ur getting me nervous

Originally Posted by 540 M-Sport

is there not a replacement harness

That's the really weird thing!

I asked and asked and asked - and I have not yet gotten a definitive answer (see earlier unanswered parts of this thread in post #51 above)

Since the trunk loom repair is so common, I was SURE the dealers would know which part number it was, but, when I called them (maybe two years ago), more than one dealer told me they'd never sold the loom.

I thought that was crazy since people MUST be going to the dealer with license-plate light problems, trunk light problems, trunk lock problems, etc. ... and the service department isn't gonna' solder a bunch of wires together.

But alas ... as long as I've looked ... NOBODY yet has definitively stated what the part number is for the trunk loom ... nor how hard or easy it is to repair.

Here's yet another picture of a trunk loom (from QSilver7) and a description of weird electrical lighting anomalies which turned out to be due to a classic broken wire.

"I had a CHECK REAR LIGHT warning (last week) on my 540iT and one of the bulbs on the passenger side was not working. After checking the bulbs (swapping them etc) which proved that both worked...I tackled checking the loom (on the Touring it was in the far right tailgate hinge)...there it was...obvious as day...a broken wire (white with a burgundy/brownish stripe). I had to get my needle nose pliers to reach into the abyss to pull the half that was way back up into the roof area of the loom. I spliced the wire back together and all is good again.

Here's a pic of Doug's e39 sedan's trunk loom...and in the "orange box" he found the same white wire broken:"

Note that the LCMIII (in the 2002 E39 anyway) will SWITCH lights when certain bulbs are out (see descriptions from QSilver7 below).

It would really be nice if others who have had the trunk-loom wiring problem and who have fixed it would post pictures of the result.

I really want to compare my (admittedly lousy) wiring repair with yours (to see what I could have improved upon).

If you had a mechanic fix the problem, then I would like to know HOW they did it (I assume they replaced the entire harness). Seeing the old harness would be instructive if you asked for your parts back.

This is a request for others to show how THEY solved this trunk loom wiring problem with pictures!